First off, I never messed with the plastic plunger on the city fill for years on my motorhome or Monty until reading about it on this forum convinced me I needed to. Never had a problem with freezing either. First year I tried it, I screwed it up just like you did.
Where we went wrong is pushing on that little plunger when we had the water pump TURNED ON. It forced back pressure against that little valve. There is a small o-ring in there that is now disoriented from it's proper seated posaition, and it is not allowing that valve to close properly. It is not broke, but will have to come apart to be put back together. I worked too hard fixing mine, as I was convinced I broke it. (the unneeded replacement part I bought is still in the garage.) My dealer set me straight after I had already taken it apart.
I again did more work than necessary, dismantling mine from the outside. On the 2955, the valve in question is accessed from inside the coach by taking out about 3 screws that held a cover over the inside of that waterfill area. The cover was covered with carpet, and right down on the floor in that rear corner.
If you can access that valve, and detach it from the water line attached to it, it will be readily seen what you need to do to fix it.
On edit, I failed to pay attention to your model # 3400. Think you guys have that coinvenience center, or whatever it's called. I suppose your city fill is there. You need to get to the back of it however you accomplish that, and you will see what's wrong.
Linear Mode
